Active noise cancelation with controllable levels

Patent metadata

Field	Value
Publication number	US-2020105239-A1
Application number	US-201916721529-A
Country	US
Kind code	A1
Filing date	Dec 19, 2019
Priority date	Oct 16, 2015
Publication date	Apr 2, 2020
Grant date	—

Abstract

A system including an automatic noise canceling (ANC) headphone and a processor. The ANC headphone has a microphone configured to generate a microphone signal and at least two non-zero ANC gain levels. The processor is configured to receive the microphone signal, determine a characteristic of the microphone signal, and identify a revised ANC level from the ANC gain levels based on a comparison of the characteristic to at least one threshold. Methods are also disclosed.

First claim

What is claimed is:

1 . A noise reduction system comprising:
an automatic noise canceling headphone having an automatic noise canceling feedforward microphone configured to generate a feedforward microphone signal, the automatic noise canceling headphone further having automatic noise canceling gain levels including at least two non-zero automatic noise canceling gain levels; and a processor configured to receive the feedforward microphone signal, determine a power value of a first frequency range of the feedforward microphone signal, determine a power value of a second frequency range of the feedforward microphone signal, and select one of the at least two non-zero automatic noise canceling gain levels based on the determined power values.

2 . The noise reduction system of claim 1 wherein determining a power value of a first frequency range comprises performing calculations on a moving window of data.

3 . The noise reduction system of claim 1 wherein the first frequency range is a low-frequency range and the second frequency range is a mid-frequency range.

4 . The noise reduction system of claim 3 wherein the processor is further configured to select one of the at least two non-zero automatic noise canceling gain levels based on a comparison of the power value of the low-frequency range to a first threshold and the power value of the mid-frequency range to a second threshold that is not equal to the first threshold.

5 . The noise reduction system of claim 1 wherein the at least two non-zero automatic noise canceling gain levels include a soft-gain level and a strong-gain level that is greater than the soft-gain level.

6 . The noise reduction system of claim 5 wherein the at least two non-zero automatic noise canceling gain levels includes a mid-gain level that is greater than the soft-gain level and less than the strong-gain level.

7 . The noise reduction system of claim 1 wherein the processor is further configured to feather an anti-noise signal between an off state and at least one of the automatic noise canceling gain levels and to feather the anti-noise signal between a first level of the automatic noise canceling gain levels and a second level of the automatic noise canceling gain levels.

8 . A method of reducing automatic noise canceling hiss in a headphone having an active noise cancellation system, the method comprising:
generating a feedforward microphone signal from an automatic noise canceling feedforward microphone; determining a power value of a first frequency range of the feedforward microphone signal; determining a power value of a second frequency range of the feedforward microphone signal; and selecting one of at least two non-zero automatic noise canceling gain levels of the headphone based on the determined power values.

9 . The method of claim 8 wherein the feedforward microphone signal from the feedforward microphone of the active noise cancellation headphone includes at least two non-zero feedforward active noise cancellation gain levels.

10 . The method of claim 8 wherein the first frequency range is a low-frequency range and the second frequency range is a mid-frequency range.

11 . The method of claim 10 wherein the selecting one of the at least two non-zero automatic noise canceling gain levels based on the comparison of the determined power levels includes selecting one of the active noise cancellation gain levels based on a comparison of the power value of the low-frequency range to a first threshold and the power value of the mid-frequency range to a second threshold that is not equal to the first threshold.

12 . The method of claim 8 wherein the at least two non-zero automatic noise canceling gain levels include a soft-gain level, a mid-gain level that is greater than the soft-gain level, and a strong-gain level that is greater than the mid-gain level, the method further comprising:
detecting whether audio is being played by an audio speaker of the active noise cancellation headphone, and
outputting a signal corresponding to the strong-gain level when audio is being played.

13 . The method of claim 8 further comprising:
feathering an anti-noise signal between an off state and at least one of the at least two non-zero automatic noise canceling gain levels; and
feathering the anti-noise signal between a first level of the at least two non-zero automatic noise canceling gain levels and a second level of the at least two non-zero automatic noise canceling gain levels.

14 . The method of claim 13 further comprising:
selectively permitting a feedforward anti-noise signal to pass from a feedforward anti-noise signal path to a feedback anti-noise signal path at an input side of a feathered gain mixer; and
selectively permitting the feedforward anti-noise signal to pass from the feedforward anti-noise signal path to an output side of the feathered gain mixer.

15 . The method of claim 8 further comprising matching the selected non-zero automatic noise canceling gain level to a predetermined audio equalizer profile.

16 . An automatic noise canceling level controller, comprising:
a first bandpass filter configured to filter a microphone signal in a first frequency range; a second bandpass filter configured to filter a microphone signal in a second frequency range; a first estimator configured to determine a first power value of the first frequency range; a second estimator configured to determine a second power value of the second frequency range; and a threshold comparator configured to select one of at least two non-zero automatic noise canceling gain levels of a headphone based on the first power value and the second power value.

17 . The controller of claim 16 wherein the first estimator is a moving-window mean-square estimator configured to determine a power value of a first frequency range comprises performing calculations on a moving window of data.

18 . The controller of claim 17 wherein the first estimator includes a programmable time constant.

19 . The controller of claim 16 wherein the first frequency range is a low-frequency range and the second frequency range is a mid-frequency range.

20 . The controller of claim 16 wherein the first bandpass filter has a center frequency lower than a center frequency of the second bandpass filter.

Assignees

• Avnera Corp

Inventors

• Kumar Amit
• Sorensen Eric

Classifications

• G10K2210/3026

  Feedback · CPC title

• G10K2210/3014

  Adaptive noise equalizers [ANE], i.e. where part of the unwanted sound is retained · CPC title

• G10K2210/1081

  Earphones, e.g. for telephones, ear protectors or headsets · CPC title

• G10K2210/3028

  Filtering, e.g. Kalman filters or special analogue or digital filters · CPC title

• G10K2210/3027

  Feedforward · CPC title